Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit a340b3e2 authored by KarimAllah Ahmed's avatar KarimAllah Ahmed Committed by Radim Krčmář
Browse files

kvm: Map PFN-type memory regions as writable (if possible) 



For EPT-violations that are triggered by a read, the pages are also mapped with
write permissions (if their memory region is also writable). That would avoid
getting yet another fault on the same page when a write occurs.

This optimization only happens when you have a "struct page" backing the memory
region. So also enable it for memory regions that do not have a "struct page".

Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: kvm@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: default avatarKarimAllah Ahmed <karahmed@amazon.de>
Reviewed-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: default avatarRadim Krčmář <rkrcmar@redhat.com>
parent e5317539

virt/kvm/kvm_main.c

+5 −2
Original line number Diff line number Diff line
@@ -1428,7 +1428,8 @@ static bool vma_is_valid(struct vm_area_struct *vma, bool write_fault) 


static int hva_to_pfn_remapped(struct vm_area_struct *vma,

			       unsigned long addr, bool *async,

			       bool write_fault, kvm_pfn_t *p_pfn)

			       bool write_fault, bool *writable,

			       kvm_pfn_t *p_pfn)

{

	unsigned long pfn;

	int r;
@@ -1454,6 +1455,8 @@ static int hva_to_pfn_remapped(struct vm_area_struct *vma, 


	}



	if (writable)

		*writable = true;



	/*

	 * Get a reference here because callers of *hva_to_pfn* and
@@ -1519,7 +1522,7 @@ static kvm_pfn_t hva_to_pfn(unsigned long addr, bool atomic, bool *async, 
	if (vma == NULL)

		pfn = KVM_PFN_ERR_FAULT;

	else if (vma->vm_flags & (VM_IO | VM_PFNMAP)) {

		r = hva_to_pfn_remapped(vma, addr, async, write_fault, &pfn);

		r = hva_to_pfn_remapped(vma, addr, async, write_fault, writable, &pfn);

		if (r == -EAGAIN)

			goto retry;

		if (r < 0)